feat: add searchable dropdown with Popover + Command pattern

Rewrite SelectField to use shadcn/ui Popover + Command (cmdk) pattern
for searchable selects, following best practices. This eliminates
console errors from the previous input-inside-SelectContent approach.

Changes:
- SelectField.js: Use Popover + Command for searchable fields
- Add Command component with CommandInput for proper search
- Update dialog.jsx to use Huge Icons instead of lucide-react
- Simplify searchable logic to follow PHP config directly

The Command component handles keyboard navigation and filtering
properly without focus event conflicts.

src/admin/components/ui/popover.js

@@ -12,16 +12,18 @@ function PopoverTrigger({ ...props }) {
 function PopoverContent({ className, align = "center", sideOffset = 4, ...props }) {
     return (
         <PopoverPrimitive.Portal>
-            <PopoverPrimitive.Content
-                data-slot="popover-content"
-                align={align}
-                sideOffset={sideOffset}
-                className={cn(
-                    "z-50 w-72 rounded-md border bg-popover p-4 text-popover-foreground shadow-md outline-none data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2",
-                    className
-                )}
-                {...props}
-            />
+            <div className="formipay-design-system">
+                <PopoverPrimitive.Content
+                    data-slot="popover-content"
+                    align={align}
+                    sideOffset={sideOffset}
+                    className={cn(
+                        "z-50 w-72 rounded-md border bg-popover p-4 text-popover-foreground shadow-md outline-none data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2",
+                        className
+                    )}
+                    {...props}
+                />
+            </div>
         </PopoverPrimitive.Portal>
     );
 }